Gaseous fuel equalizing system for nonuniformly firing engines



Patented July 6, 1954 GASEOUS FUEL EQUALIZING SYSTEM FOR NONUNIFORMLY FIRING ENGINES Owen L. Garretson, Roswell, N. Mex.

Original application July 21, 1949, Serial No.

1950, Serial N0. 161,418

Claims.

This invention relates to carburetion systems for supplying gaseous fuel to internal combustion engines, and is directed to such systems that employ liquefied petroleum gas as a fuel, including improved pressure regulator and fuel delivery control apparatus for regulating the flow of gaseous fuel to the carburetor. This invention is a division of my pending application, Serial No. 106,022, filed July 21, 1949, and now abandoned, and is particularly directed to means for obtaining smooth, uniform operation on gaseous fuel burning engines during acceleration and during normal operation of engines having cylinders that nre at non-uniform time intervals.

A principal object of the invention is to correct for the effects of lag or inertia in the gas pressure regulating and supply means. Such effects are apparent during acceleration and are particularly noticeable in multi-cylinder internal combustion engines that are arranged so that the cylinders are nred at non-uniform intervals of time. In such engines when one of the cylinders initiates fluid flow in the induction system, the cylinder that res immediately thereafter may receive a richer or a leaner mixture due to the lag or time delay inherent in gaseous fuel regulator systems, and different mixture strength which results in uneven power impulses from the cylinders.

Other objects of the invention are to accumulate a volume of gas during one portion of the cycle of an engine and deliver it to the intake manifold during the induction portion of the cycle, and to control the pressure head on the gas during its delivery so as not to interfere with the operation of the engine or of the regulating means.

The manner in which these and other objects and advantages are obtained will be apparent from the following detailed description of a preferred embodiment of my invention.

In the drawings, the iigure is a semi-diagrammatic view of a preferred installation of a gaseous fuel system for internal combustion engines embodying the present invention.

Referring more particularly to the drawings, the device will be described as installed on a farm tractor powered by a liquid cooled internal combustion engine. Applicant employs a simple, semi-universal cylinder and regulator mounting arranged so that a comparatively few models of the mounting may be installed on a comparatively large variety of tractors. The mounting of the container including the mounting bracket are disclosed and claimed in my copending app ication, Serial No. 161,417, flled May 11, 1950,

Divided and this application May 11,

As seen in the drawings, the tractor T may have a radiator grill G behind which is the usual radiator R connected to the liquid cooling system of the engine for dissipating rejected heat of combustion. Mounted by applicants novel bracket assembly A in front of the radiator is a high pressure container or cylinder I0 for a liqueed fuel gas, such as propane, butane and the like, or a mixture thereof.

The bracket A includes a platform i3 for the base of the container mounted on the tractor by a pair of rearwardly-extending arms i5. In a typical installation arms l5 may receive bolts Il connected to the forward end portions of the side beams I3 of the chassis of the tractor, or to any other suitable portion of the tractor chassis.

An upper clamping and steadying structure for the container is mounted upon the platform by braces 20 which support a plate 2l extending from which are strap members 23 and a clamp device 24 holding the container in place, all as described in detail in my aforesaid pending application.

As seen in the drawings, in addition to the container l0, the gaseous fuel system comprises a shut-off valve V, a high-pressure regulator H, a low-pressure regulator B, suitable piping, and an equalizer E. The construction and operation of the carburetor and regulator units of a preferred system is described in detail and claimed in my copending application, Serial No. 161,419, filed May 11, 1950. The shut-off valve V has a hand wheel 42 for the opening and closing of the valve, and may be provided with a relief valve 43. A flexible hose 44 or the like connects the valve V with the high-pressure regulator H which is provided with a pressure gauge it and a screw Ill for adjusting the regulator to the pressure desired. The high-pressure regulator H discharges gaseous fuel at a pressure somewhat above atmospheric pressure into a low-pressure regulator or controller generally indicated at B.

Regulator B has upper and lower casing members and 5I separated by a diaphragm 52, to form an upper fuel regulating chamber 53 to deliver fuel in accordance with engine demands, and a lower compensating air chamber 54 to maintain the desired air-fuel ratio. As shown in detail in my copending application, Serial No. 161,419, filed May 11, 1950, the regulator has an inlet valve 56 opening into the upper chamber 53 and controlled by valve-actuating mechanism 51 mounted on the diaphragm 52. The inlet valve 5t is connected to the high-pressure regulator 1-1 as at 58 for reception of fuel therefrom.

An air bleed inlet orice 60 is formed in the wall or casing 5| and an air outlet orifice Gila connects chamber to pipe iii. Filter material 6| maybe retained over the orifice til by a cap S2 having an air inlet aperture t3. The orifice 5i) is preferably smaller in area than the orifice 60a.

The upper chamber of the regulator is connected to a fuel delivery pipe lili which is connected to a pipe T itt. A pipe |93 has one end connected to the pipe T |62 and its opposite end connected to a fitting we. Fitting les is connected to the Venturi throat i335 of the carburetor ist ci the engine by means oi the gaseous fuel jet lill. A needle valve screw |88 is mounted in the tting for providing an adjustable restriction to the flow of gas from the pipe |533 into the carburetor.

The lower chamber 54 of the regulator is connected to a pipe E i i the opposite end of which is connected to a second pipe T I2. A pipe i3 leads from the pipe T lili and communicates with the carburetor itil in what may be termed an intermediate pressure zone I, which zone preferably lies between the choke butterfly valve lill and the Venturi throat H45. An air intake pipe i 54a is connected to the carburetor and in accordance with usual practice may lead to an air iilter or similar air cleaning device. A throttle valve is mounted adjacent the manifold end of the carburetor venturi for controlling the flow of the fuel mixture to the manifold H6.

Applicants novel equalizer device is generally indicated at E. It comprises upper and lower housings l |'i and H8, respectively, which are provided with out-turned annular flanges ii and |2t, respectively. A loose diaphragm |2| has its peripheral edge portion clamped between the flanges il@ and |20. The diaphragm |2| divides the equalizer E into an upper fuel gas receiving chamber |22 and a lower air receiving chamber |23. A nippleiili connects the chamber |22 with the T-coupling |62 in the fuel line and a similar nipple |25 connects the 'chamber |23 with the T- coupling iii the compensating air line. The diaphragm iti has suicient slack to permit it to move freely between a position in which it is bowed into the chamber |22, and a position in which it is bowed into the chamber |23. The diaphragm i2! is preferably biased very slightly into the chamber |23, and in the illustrated embodiment this accomplished by mounting the equalizer E with the diaphragm horizontal so that its weight moves it into the chamber 23. Such bias, however, is not essential.

in its broader aspects the present invention is not limited to any particular type of regulator or to the interconnections by the pipes iii and l i3 between the equalizer chamber |23, the regulator chamber les and the carburetor inlet. The invention also includes, however, a novel combination of regulator and equalizer, the combination disclosed constituting the preferred embodiment.

ln this combination, the orice ttaopening into the regulator chamber 54 is connected by the pipes ||i and H3 with the intermediate zone I of the carburetor, so that the reduced pressures existing in zone I are applied to the chamber 23 and higher pressures of predetermined ratio to the pressures in zone l are applied to the chamber 54.

As previously stated, the equalizer E is intended primarily for use with engines having two or more cylinders with an uneven iiring order but is also useful in connection with any type of engine to eliminate the effect of lag in the regulator during rapid acceleration or iluctuations in the intake velocity, and to permit the use of a less sensitive regulator. For example, the disclosed embodiment of the invention may be used with a two-cylinder, four-cycle engine having the cylinders in line on the same side of the crankshaft with cranks displaced 180. In such engines there is necessarily a shorter time interval between the iiring of #l and #2 cylinders than between #2 and #l cylinders, the shorter interval being 189 of crankshaft rotation and the longer interval being 540 of rotation. Likewise, there is substantially continuous intake suction for the first 360 oi rotation and none for the next 360 of rotation in the cycle.

The regulator B, regardless oi its particular construction or the details of its operation, is designed to remain closed so as to prevent any ilow of fuel through the valve lit when atmospheric pressure exists in the carburetor |36. When the engine is running air is inspired by the cylinders on their intake strokes tl 1ough the carburetor and the intake pipe iilc. The flow of air through the pipe iic and the air filter, if any, produces a pressure drop in the intermediate zone l which increases with an increase in the velocity of the air iiow. A further pressure drop is produced by the restriction of the venturi 55 which also increases with increasing now, but at a greater rate than the increase of the pressure drop in the intermediate zone l. The pressure drop in the Venturi throat l5 is transmitted past the needle valve w8 through the pipes |63 and 50| to the regulator chamber 553 causing the regulator valve 55 to open so that fuel liows at a sub-atmospheric pressure through the jet i'. where it is mixed with the air stream in the Venturi throat U35 to provide a combustible mixture. Preferably, substantially all of the pressure drop between the regulator chamber 53 and the Venturi throat occurs at the needle valve H38 and the regulator is governed so as to provide increasing amounts of fuel with increasing amounts of air flow through the venturi to maintain the desired mixture ratio throughout the operating range.

With the beginning of air new through the Venturi throat i, starting from atmospheric condition, the pressure drops in the intermediate zone l and this pressure drop is transmitted through the pipe H3 to the chamber E23 of the equalizer. While in the illustrated embodiment the chamber |23 is connected to atmosphere through the oririces et and Elia, these are made relatively small compared to the diameter of the pipes and Il?, so that substantially all of the pressure drop occurs through the orifices and the pressure in the chamber |23 remains substantially the same as the pressure in the intermediate zone l. At the same time the greater pressure drop occurring in the Venturi throat m5 is transmitted through the pipe |93 to the equalizer chamber 22 and through pipe mi to the regulator chamber 53. Before the pressure has dropped suiciently to cause the valve 5t to open, the pressure in chamber |22 is less than that in the chamber |23 so that the diaphragm HI is urged upwardly into the chamber |22. As soon as the pressure drop transmitted through the pipe is suncient to overcome the bias of the regulator valve towards closed position and the inertia of the regulator, the valve 56 opens to admit fuel into the line il. However, so long as the pressure drop produced in the chamber |23 by a particular rate of ilow through the intake pipe is less than the pressure drop required to be maintained in the regulator chamber 53 in order to overcome the bias of the regulator towards closed position, the diaphragm |2| continues to be urged towards its upwardly bowed position in which the volume of chamber i 22 is a minimum. With a regulator of given sensitivity, this condition exists at low rates of air now through the carburetor, as when the throttle valve I5 is only slightly opened.

Under these conditions when the air now through the carburetor stops, as it does after the intake period of the two cylinders in the type of engine described above, the pressures rise and approach atmospheric throughout the system. The inertia of the moving parts of the regulator permits the pressure in the regulator chamber 53 to rise beyond the regulated delivery pressure before the valve 55 is fully closed. Thus, the pressure in the regulator chamber 53 and in the pipes and |03 increases slightly above atmospheric pressure just as the regulator closes. In the absence of any correction, therefore, this positive pressure in the pipes ||l| and |03 would cause gaseous fuel to flow through the jet |01 into the air at atmospheric pressure in the carburetor |6 and manifold 6. Thus, at the beginning of the next suction period an over-rich mixture would be delivered into the rst cylinder if the engine were operating with the throttle valve only slightly open or if the regulator had substantial inertia, since the amount of fuel permitted to bl-eed into the carburetor between suction periods would be a substantial percentage of the inspired charge for one cylinder.

However, with the present invention when the engine and regulator are operating under these conditions the increase of pressure in the regulator chamber 53 and the pipes lill and |03, as the regulator closes, moves the diaphragm |2| from its uppermostposition toward its lowermost position, increasing the volume of the chamber |22. This increase in volume takes care of the extra fuel and prevents the pressure in the pipe |03 from rising above atmospheric pressure so that the fuel is not bled into the carburetor between the suction periods.

On the other hand, when the engine is operating with greater throttle openings producing relatively large pressure drops in the intermediate zone I and in the Venturi throat |35 compared to the pressure required to overcome the bias of the regulator towards closed position, when the suction starts the pressure in chamber |22 is lower than the pressure in chamber |23 in the same manner as described above until after the regulator valve 53 opens. build up, however, the regulator delivers more gas at the regulated pressure while the pressure in the chamber |23 continues to fall until it is less than the pressure in the chamber 22 so that the diaphragm i 2| is moved downwardly into chamber |23, charging the chamber |22 with gas. Under these conditions, when the suction stops, the chamber |22 being already fully charged cannot receive the additional amount of gas delivered by the regulator as it closes so that the pressure in the pipes IDI and ID3 may become slightly positive and some gas may be bled into the carburetor through the jet |07. However, under these conditions of operation the amount of gas bled into the carburetor between suction Y periods is only a small percentage of the volume inspired by one cylinder and thus does not appreciably change the mixture ratio.

Thus when an engine of the type described including unevenly firing cylinders is operating As the suction continues to either at small throttleropenings or at full throttle openings the chamber |22, at the beginning of each suction period, is lled with gas and has a volume greater than its minimum volume, whether this charging of the chamber |22 occurred as a result of the inertia of the regulator in closing, or as a result of the change in the pressure relations during the previous suction period, as described above. Thus, at the beginning of each new suction period, gas is delivered by the equalizer chamber |22 into the line iii as soon as the suction starts and before the pressure drop has become sufiicient to open the regulator valve 56. At the same time that the gas is being delivered from the chamber |22, the regulator valve 55 begins to open so that fuel in the proper quantity is available to be mixed with the incoming air as soon as each suction period starts and throughout that suction period regardless of the extent of the throttle opening. This is particularly important when the engine is running at high speed or with the throttle fully opened since otherwise the rst cylinder Would be starved relative to the second cylinder because of the delay in getting the gas from the regulator to the Venturi throat while the first cylinder is inspiring its charge, which delay does not occur when the second cylinder continues the suction period.

In the particular pressure regulator arrangement disclosed, the high pressure regulator H may be set to deliver gaseous fuel to the low pressure regulator B at about 5 to l5 p. s. i. above atmospheric pressure. The low pressure regulator B is biased to hold the valve 56 closed under balanced pressure conditions and in the embodiment illustrated this is effected by arranging the regulator B with its diaphragm horizontal so that the weight of the diaphragm and the valve linkage 5l connected thereto is suflicient to hold the valve 56 closed against pressure of the gas from the high pressure regulator. Preferably the regulator is made sensitive to slight decreases in pressure in the upper or regulating chamber 53 so that the valve 56 is opened by the pressure drop in the Venturi throat |05 when the engine is turned over at cranking speeds.

During a suction period occurring in normal running of the engine the sub-atmospheric pressure existing in the zone I is not only transmitted to the equalizer chamber |23 but is also transmitted through the pipe l to the orifice @da opening into the regulator chamber 5d. However, the entire pressure drop existing in the zone I is not applied to the chamber 5-3 since atmospheric air is admitted to the chamber 54 through the orice 6|! and ows into the pipe i i through the orii'lce 60a, so that a predetermined fraction of the pressure drop existing in the zone l is established in the regulator chamber 5d and applied to the underside of the diaphragm 52.

In one practical embodiment of the invention which has been found to operate satisfactorily the orifice 60a is made l@ of an inch in diameter and the orice 60 is made of an inch in diameter, the pipes l I and I3 being of substantially larger diameter so that substantially all of the pressure drop occurs at the orifices. With this arrangement about 3A of the pressure drop occurring in the intermediate zone I is applied to the charnber 54.

As the throttle l5 is opened and the air speed through the carburetor increases an increasing pressure drop is applied to the pipe i i3 and the same pressure drop, plus a further pressure drop producedV by the Venturi restriction and increasing at a faster rate is applied to the jet |01. Only a slight pressure differential between the chambers 53 and 5|! is required to overcome the bias of the regulator' valve and open the valve 56 to admit gaseous fuel from the high pressure regulator H into the regulator chamber 53. The valve automatically opens and closes to admit the proper amount of fuel to maintain this slight pressure diiferential between the two chambers 53 and iid. rIhus as the pressure in the Venturi throat |85 decreases with increased throttle openings and consequent increased rates of air how, the pressure drop between the chamber 53 and the discharge end of the jet Mil, most of which occurs at the valve |03, increases while the pressure in the regulator chamber 54 remains a slight amount higher than the pressure in the regulatoi` chamber 53, just suflicient to overcome the bias of the regulator valve towards closed position.

The pressure head on the air entering the throat of the venturi, which head determines the amount of air which flows into the Venturi throat and is mixed with the fuel entering through the jet EST, is not the diference between atmospheric pressure and the pressure in the Venturi throat, but on the contrary is the difference between the pressure in the zone I at the entrance to the venturi and the pressure in the throat. The pressure in zone I is always less than atmospheric pressure when the engine is running, and decreases as the throttle opening increases, Thus if the pressure in the regulator chamber 54 were made equal to the pressure in zone I at all throttle openings, the pressure head applied to the fuel would be equal to that applied to the inspired air at all throttle openings. However, due to the fact that the ratio of the specific heat of air at constant pressure to its specific heat at constant volume is greater than the corresponding ratio for liqueed petroleum gas, such as propane and butane and mixtures thereof, the mixture would become slightly leaner with increased iiow if exactly balanced pressures were maintained, since the weight of fuel inspired would not increase in constant ratio with the weight of air inspired. Thus to maintain a constant mixture ratio it is necessary to increase the pressure head on the fuel at a rate slightly greater than the rate at which the pressure head on the air entering the Venturi throat increases with increasing throttle openings.

In addition, it is desirable from the standpoint of fuel economy to enrich the mixture slightly 'to the ratio for maximum power at full throttle opening, and lean it to the mixture ratio producing maximum economy at small throttle openings. Accordingly, the orifices il and Sila are selected to apply a percentage of the pressure drop in zone I to the chamber 5c, so that the pressure head on the fuel delivered by the regulator to the needle valve 58 increases with increased throttle opening at a greater rate than the pressure head on the air while the pressure in the equalizer chamber |23 varies with the pressure in zone I.

Part or all of the desired increase in the pressure head on the fuel with respect to the pressure head on the inspired air may also be obtained by the mounting of the regulator valve 56 for reciprocation in the fuel inlet passage, as illustrated, and as disclosed more in detail in my said application Serial No. 161,419, filed May ll, 1950, so that the regulator valve restricts the fuel passage, producing a pressure drop acting to open the valve and increasing with increasing rates of iiow. When the entire variation of the pressure head on the iuel is obtained in this manner it is unnecessary to Vary the pressure in the equalizer chamber |23, and this pressure may remain atmospheric or substantially so, while the pressure in the pipes itil and |33 and in the chamber |22 varies above and below atmospheric with variations in the throttle opening.

Thus in the illustrated embodiment of the invention, the pressure at which gas contained in the chamber il is delivered to the pipe |83 at the beginning of a suction period is always subatmospheric, and falls as the suction increases. This is because the pressure `acting on the gas in the chamber |22 is the pressure in the chamber |23 less the weight of the diaphragm lZi, and the pressure in chamber |22 falls with the pressure in the zone I of the carburetor as the air velocity therethrough increases. A t the same time, the pressure in chamber 5t of the regulator B is reduced a lesser amount, by about threefourths of the pressure drop in the zone I and the chamber 23 in the example given, so that the difference between the pressure in the chamber 5ft and the delivery pressure of the gas from the chamber 22, which difference increases with increasing suction, acts in a direction to open the regulator valve 55.

Stated in another way, as the air velocity through the carburetor builds up from rzero to the maximum permitted by the particular throttle opening, the pressure head on the fuel delivered from the chamber H22 past the needle valve itt builds up with the difference between the pressure drops in the zone I and the Venturi throat its, less the force required to overcome the slight bias of the diaphragm ii and the inertia thereof and at the saine time the pressure head available to deliver fuel from the regulator B past the needle valve Hill builds up at a raster rate, in accordance with the diference between the pressure drop in the Venturi throat Iiii and a fraction, such as three-fourths, of the pressure drop in the zone I, less the force required to overcome the bias of the regulator diaphragm and the inertia thereof and of the valve operating linkage 5l connected thereto. ri'fhus the pressure heads start at the same time and build up simultaneously. Because of the lower bias and inertia of the diaphragm lill fuel is delivered from the chamber before the regulator valve opens while before the suction has attained its maximum value in the case of relatively wide throttle openings, the differential pressures on the diaphragm` h2 have become sufficient to open the regulator valve 5S and fuel is delivered from the regulator at a higher pressure head. rIhe delivery of fuel from the regulator to the pipe itl at a pressure higher than the pressur in the chamber E23 reverses the pressures acting upon the diaphragm l2! so that this diaphragm moves downwardly into the chamber |223 whether or not all of the fuel gas contained in the chamber 22 had been delivered to the pipe ll.

Thus the action of the equalizer E delivering fuel contained therein into the fuel line leading to the carburetor does not interfere either with this action of the regulator or with the proper action of the engine since the fuel is delivered at a rate to maintain the proper mixture ratio.

In case the throttle opening and the sensitivity of the regulator' B are so related that the difference between the pressures in the chambers 5B and |23 is not equal to the amount required to overcome the cias of the regulator towards closed position, the equalizer chamber |22 delivers all of its contained fuel to the pipe |03 and the pressure in the pipes |83 and 10| thereafter' falls sufficiently to complete the opening of the regulator valve. In such cases, however, the pressure in the chamber |22 does not exceed the pressure in the chamber |23 during the suction period and the chamber |22 contains only the small amount of fuel with which it was charged as a result of the inertia of the regulator in closing after the previous suction period. Nevertheless, the operation of the engine is improved since the lag between the end of the delivery of the fuel from the chamber |22 and the beginning of the delivery from the regulator is less than it would have been if the differential pressures on the regulator diaphragm had not started to build up during the period the equalizer chamber |22 was discharging. y

Thus,.the equalizer, which is a compactand simple device, and which may be quickly and easily installed, has the smoothing attributes of a very large reservoir on one hand, and yet on the other hand does not reduce the sensitivity of the regulator as would such a reservoir.

As an example of a typical installation with a two-cylinder, four-cycle engine of about 200 to 500 inches displacement, and with a regulator constructed in accordance with the above specific example, the system operates satisfactorily with an equalizer diaphragm of about six or seven inches in diameter.

While a preferred embodiment of the invention has been disclosed in considerable detail, it is to be understood that the invention is not limited thereto, and that numerous changes and rearrangements of parts may be resorted to without departing from the scope of the invention as defined in the following claims.

What is claimed is:

l. A gaseous fuel system for an internal combustion engine having a fuel induction system including an intake pipe with a throttle valve and a^`venturi therein, comprising a regulator having an inlet adapted to be connected to a source of gaseous fuel under pressure and an outlet adapted to deliver such gaseous fuel at a reduced. regulated pressure, a fuel conduit for connecting said outlet to the venturi in the intake pipe of the engine, and an equalizing device having a fuel chamber `and an air chamber separated by a movable pressure responsive element, a connection between said equalizer fuel chamber and said fuel conduit for conducting fuel to and from said equalizer fuel chamber, and a conduit for connecting said equalizer air chamber to the intake pipe of the engine upstream from the venturi therein, said conduit being constantly open for free now of air into and out of said air chamber whereby movement of said pressure responsive element in response to differential pressures in said chambers creates flow of air through said conduit so that the pressure in said air chamber is substantially unaffected by movement of said pressure responsive element.

2. A gaseous fuel system for an internal combustion engine having a fuel induction system including an intake pipe with a throttle valve and a venturi therein, comprising a regulator having m inlet adapted to be connected to a source of gaseous fuel under pressure and an outlet adapted to deliver such gaseous fuel at a reduced regulated pressure, a fuel conduit for connecting said outlet to the venturi in the intake pipe of the engine, an adjustable restriction in said fuel conduit, and an equalizing device having a fuel chamber and an air chamber separated by a movable pressure responsive element, a ,connection between said equalizer fuel chamber and said fuel conduit upstream from said adjustable restriction for conducting fuel to and from said equalizer` fuel chamber, and a conduit for connecting said equalizer `air chamber to the intake pipe of the engine upstream from the venturi therein, said conduit being constantly open for free flow of air into and out of said air chamber whereby movement of said pressure responsive element in response tol differential pressures in said chambers creates iiow of air thro-ugh said conduit so that the pressure in said air chamber is substantially unaffected by movement of said pressure responsive element,

3. In a gaseous fuel system of an internal combustion engine having an .air intake pipe and a gaseous fuel conduit opening into said pipe, an equalizing device comprising a fuel receiving chamber and a control chamber, a loose diaphragm sealed between said chambers, said diaphragm being subjected to the fluid pressures in said chambers and being movable into and out of said chambers to vary the volume thereof, a passageway for connecting said fuel receiving chamber with the fuel conduit connecting a source of fuel to the engine, and a passageway for connecting said control chamber with the air intake pipe of such engine, both of said passageways being constantly open for free flow into and out of said chambers whereby movement of said diaphragm in response to differential pressures in said chambers creates flow of air through said control chamber passageway so that the pressure in said control chamber is substantially unaffected by diaphragm movement.

4. In a gaseous fuel system of an internal combustion engine having an air intake pipe and a gaseous fuel conduit opening into said pipe, an equalizing device comprising a fuel receiving chamber and a control chamber, a movable pressure responsive element subjected to the fluid pressures in said chambers and movable into and out of said chambers to vary the volume thereof, a passageway for connecting said fuel receiving chamber with the fuel conduit connecting a source of fuel to the engine, and a passageway for connecting said control chamber with the intake pipe of such engine, both of said passageways being constantly open for free flow into and out of said chambers whereby movement of said pressure responsive element in response to differential pressure in said chambers creates flow of air through said control chamber passageway so that the pressure in said control chamber is substantially unaffected by movement of said pressure responsive element.

5. An equalizing device for a gaseous fuel system of an internal combustion engine having an air intake pipe and a gaseous fuel conduit opening into said pipe, comprising a fuel receiving chamber and a control chamber, a movable pressure responsive element subjected to the fluid pressures in said chambers and movable into and out of said chambers to vary the volume thereof, said element being biased into said control chamber by a substantailly constant force, a passageway for connecting said fuel receiving chamber with the fuel conduit connecting a source of fuel to the engine, and a passageway for connecting said control chamber with the intake pipe of such engine, both of said passageways being constantly open for free flow into and out of said chambers whereby movement of said pressure responsive aceaoea element in response to differential pressure in said chambers creates flow of air through said control chamber passageway so that the pressure in said control Chamber is substantially unaffected by movement of said pressure responsive element.

6. An equalizing device for a gaseous fuel system of an internal combustion engine having an air intake pipe and a gaseous fuel conduit opening into said pipe, comprising a fuel receiving chamber and a Control chamber, a movable pressure responsive element subjected to the fluid pressures in said chambers and movable into and out of said chambers to Vary the volume thereof, means for mounting said equalizing device with said control chamber below said element, so that said element is biased only by its own weight into said control chamber, a passageway for connecting said fuel receiving chamber with the fuel conduit connecting a source of fuel to the engine, and a passageway for connecting said control chamber with the intake pipe of such engine, both of said passageways being constantly open for free ow into and out of said chambers whereby movement of said pressure responsive element in response to differential pressure in said chambers creates now of air through said control chamber passageway so that the pressure in said control chamber is substantially unaffected by movement of said pressure responsive element.

7. An improved liqueiied petroleum gas carburetion system for a tractor or the like comprising a controller having a diaphragm therein for dividing said controller into two chambers, a valved gas inlet passage to the rst 'chamber and an outlet passage leading to the carburetor from the first chamber, an atmospheric air inlet to the second chamber and an outlet passage leading from the second chamber to the main air intake at a point downstream of the choke valve, a lever mechanism connected to the diaphragm and adapted to open and close the gas inlet passage, and a fuel accumulator having two chambers, one

of which communicates with the gas outlet passage and the other of which communicates with the atmospheric air outlet passage.

8. An improved liquefied petroleum gas carburetion system as claimed in claim 7 characterized by the fact that a gas supply container for the gas inlet passage is provided, that supporting means for the container is adapted to be mounted on the tractor, and that said controller is also mounted on said supporting means,

9. An improved liquefied petroleum gas carburetion system as claimed in claim 7 characterized by the fact that a control valve is disposed between the gas chamber of the controller and the carburetor.

10. A gaseous fuel system for an internal combustion engine having a fuel induction system including an intake pipe with a throttle valve and a venturi therein, comprising a regulator having an inlet adapted to be connected to a source of gaseous fuel under pressure and an outlet adapted to deliver such gaseous fuel at a reduced regulated pressure, a fuel conduit for connecting said outlet to the venturi in the intake pipe of the engine, and an equalizing device having a fuel chamber with a movable pressure responsive element, a connection between said equalizer fuel chamber and said fuel conduit for conducting fuel to and from said equalizer fuel chamber, and means for establishing reference pressures on the opposite side of said pressure responsive element greater than the pressure in said fuel chamber at minimum rates of flow through said regulator and less than the pressure in said fuel chamber at maximum rates of ilow, said means including an opening to atmosphere open for flow both toward and away from said pressureresponsive element, whereby movement of said pressure responsive element in response to differential pressure between said chambers creates a flow of air through said opening so that said referenced pressure is substantially unaffected by movement of said pressure responsive means.

References Cited in the file of this patent UNITED STATES PATENTS Number' Name Date 389,423 Wood June 2, 1908 1,422,987 Keith et al. July 13', 1922 1,796,126 Smith Mar. 10, 1931 2,352,003 Poinsignon June 20, 1944 2,394,401 Overbeke Feb. 5, 1946 

10. A GASEOUS FUEL SYSTEM FOR AN INTERNAL COMBUSTION ENGINE HAVING A FUEL INDUCTION SYSTEM INCLUDING AN INTAKE PIPE WITH A THROTTLE VALVE AND A VENTURI THEREIN, COMPRISING A REGUALTOR HAVING AN INLET ADAPTED TO BE CONNECTED TO A SOURCE OF GASEOUS FUEL UNDER PRESSURE AND AN OUTLET ADAPTED TO DELIVER SUCH GASEOUS TO A REDUCED REGULATED PRESSURE, A FUEL CONDUIT FOR CONNECTING SAID OUTLET TO THE VENTURI IN THE INTAKE PIPE OF THE ENGINE, AND AN EQUALIZING DEVICE HAVING A FUEL CHAMBER WITH A MOVABLE PRESSURE RESPONSIVE ELEMENT, A CONNECTION BETWEEN SAID EQUALIZER FUEL CHAMBER AND SAID FUEL CONDUIT FOR CONDUCTING FUEL TO AND FROM SAID EQUALIZER FUEL CHAMBER, AND MEANS FOR ESTABLISHING REFERENCE PRESSURES ON THE OPPOSITE SIDE OF SAID PRESSURE RESPONSIVE ELE- 